Photographic elements containing protein color formers



. er compositions from vegetable proteins.

other object is to provide new and useful color Patented Apr. 2, 1946-UNITED STATES PATENT orrics CONTAINING PROTEIN COLOR FOBMEBS Andrew B,Jennings, New Brunswick, N. J., as-

lignor to E. I. du Pont de Nemours & Company, Wilmington, Deb, acorporationofDelawai-e Nc Drawing.

' comma This invention relates to coloryielding coinpositions and tophotographic elements and proc- Homolka, Fisher and Siegrist discoveredthe utility of and established the practicability of forming dye imagessimultaneously with the development'of latent silver salt images. Colorformers which are immobile in the conventional gelatin silver saltlayers of photographic elements during photographic processing havereceived considerable attention by the research workers in the art.-

It has been found, however, that the addition of color formers oftenhasa deleterious effect on the light sensitivity of emulsions.

This invention has for an object the preparation of new hydrophiliccolor formers or dye intermediate compositions containinglight-sensitive silver salts or grains. A further object is to providesuch compositions from available raw materials by a simple andeconomical procedure. A still further object is to provide new colorformforming silver salt layers; Yet another object is to prevent thecoagulation and sedimentation of silver salts in photographic layers.Still other objects are to provide new photographic elements andphotographic processes and to make a general advance in the art of colorphotography and high molecular Weight, water-permeable dyeintermediates. K

- The above objects'may be accomplished in accordance with thisinvention which will be described below with greater particularity.

It has been found that vegetable proteins which are capable of beingcast into transparent films which are water-permeable can be convertedinto novel hydrophilic color formers by condensing them with abi-functional condensation agent and'a color former eithersimultaneously or step wise. The bi-functional condensing agents linkwith vegetable protein molecule to the color former nucleus thus forminga single organic compound. .In general, the condensation can beadvantageously carried out by means of aldehydes, e. g., formaldehyde ora formaldehydeyielding material or substance such as paralde-Application May 6, 1944, Serial No. 534,520

hyde, trioxane, hexamethylene-tetramine, etc.; dimethylolurea and itsmonoand di-methyl and -ethyl ethers.

The condensation may effectively be carried out in the presence of asolvent medium such as water, acids such as acetic or formic; a volatilealcohol, e. g., methanol, ethanol, etc. an ether, e. g., di-isopropylether, dioxane, etc., or mixtures of the aforementioned. Alternatively,non-solvents for the protein may be employed such as a hydrocarbon, e.g., benzine, benzene, toluene,

Condensation -tetrahydr0naphthalene, etc. agents or catalysts which areknown topromote esterification or saponification reactions such asorganic or inorganic acids, e.'g., hydrochloric, sulfuric, phosphoric,acetic, etc.; alkalies such as sodium carbonate, sodium hydroxide, etc.,may be employed as desired or if necessary to facilitate i the reaction.

The invention can be applied with any dye intermediate or color formerwhich will condense with formaldehyde to form his or polymeric compoundwithout permanently destroying-the dye coupling structure of saidintermediate. For instance, any color former which is capable ofcoupling with the development'products of primary aromatic aminodeveloping agents that are formed upon the color coupling development ofsilver salt latent images and form azomethine or quinoneimine (includingindophenol, indoamine and indoaniline) dyes can be used. It is advisableto use non-colloidal simple dye intermediates or color formers becausethe colloidal type and high molecular weight type tend to form resinouswater-impermeable condensation products. The

simple crystalline color formers which are useful in color-developersolutions thus can be easily converted into hydrophilic colorformerswhich can be used as the sole binding agents for light: sensitivesilver salts in thin photographiclayers.

The dye intermediate nuclei or color "foii'ner components of thevegetable protein-dyeintetmediates have as the active couplinggroups awhere X is an HO radical or an REM radical;

eral formula where R is hydrogen, an alkyl or substituted alkyl group,e. g., methyl, ethyl, dodecyi, betachioroethyl, betahydroxyethyl,benzyl, etc. and n is O or 1. Thus X may be a primary or secondary aminogroup. These groups are found in reactive methylene dye intermediates orcolor formers and in 2 4 sponsor aromatic hydroxyl and amino compoundsand includ a reactive ethenol, aminoethenyl, 4 hydrox and i-arnino 1,3-butadienyl groups.

.These groups occur in phenols, naphthols, .ani-

lines, naphthylamines, acylacetamides, cyanoaoetamides, beta-ketoesters,pyrazolones, N-homophthalylamines, homophtl'ialylimides, couma ranones,indoxyls, thioindoxyls, etc.

The reactive ethenol group represented by no-e. .cnoccurs in phenols andnaphthols which couple in the ortho positions and in the alkali-solubleor enol form of most reactive methylene dye intermediates. Thesereactive methylene groups have a hydrogen rendered mobile by theproximity of certain unsaturated groups such as for example,

v -(L/=O,J3=N- -.C:N and others. The CH2 group is usually presentbetween two such groups, for example, -COCH=CC-, -COCH:CN,

in a cyclic or acyclic system.

The reactive aminoethenyl group,

. arm-(Lonoccurs in aromatic amino compounds which couple in the orthoposition. e

The d-hydroxyand 4-amino-L3-butadienyl groups represented as foginhibiting agents, e. g., benzimidazoles,'etc., spectral sensitizinzdyes, stabilizers, and/or other emulsion constituents. Instead of usingthe diss persion it may be set and/or shredded and stored for lateruse.

Instead of precipitating the silver salts directly in the hydrophilic,vegetable protein dye intermediate derivatives, they may be precipitatedin a sensitive gelatin solution which is diluted and centrifuged and thesilver salts made into a paste and redispersed in the aforesaidderivatives by admixing from an aqueous solution.

The novel dye intermediates hereof have two components (1) the proteinnucleus and-(2) a plurality of dye intermediate nuclei which are joinedby the residue of the bi-functional condensation agent. In the case offormaldehyde the linking radical is a -CHaradical.

Various useful characteristics arepossessed by the novel chemicalproducts hereof. Thus the hydrophilic protein dye intermediates have (1)the ability to form strong coherent supported films, (2) a goodprotective colloid action with respect-to, silver halide grains orcrystals, (3) good permeability in the form of layers or films to waterand aqueous developing and fixing solutions, (4) optical clarity, (5)good resistance to deformation in water or aqueous media at ordinarytemperatures, (6) good dye coupling properties yielding dyes of goodsaturation of color,

and (7) good resistance to abrasion.

The invention will be further illustrated but is not intended to belimited by the following examples in which all operations were carriedout under conditions which would not expose the silver salts.

Example 1 A solution of 8.0 gms. of saligenin, M. P. 85-86 .C. in 125cc. of alcohol and 175 cc. of water was added at'15-20 C. to 55.5 cc. of37% formaldethe coupling reaction, e. g., halogen, sulfonic acid,

carboxylic acid, etc.

Vegetable proteins such as gluten, gliadens, glutenins, globulins,legumins,- glutins, and especially the zeins can be converted intoproteindye intermediates or color formers which form strongself-supporting and/or supported thin films which are freely waterpermeable'but do not dissolve in coldwater e. g., below 30 C. They havea softening point of at least 50 C. which is an advantage since itenables the photographic elements to be processed at tropicaltemperatures with safety. The vegetable protein color formers aresoluble to the extent of at least 5 parts per hundred of an aqueousalcohol solvent mixture containing 50% or less ethanol.

Light-sensitive silver halides can be precipitated in an aqueous alkanolsolution of the hydrophilic vegetable, protein color formers by addingan aqueous solution of a water-soluble bromide, er g., ammonium bromideand then an aqueous solution. of a water-soluble silver salt, e. g.,silver nitrate can be added from an aqueous solution Silverhalide, e.g., silver bromide is precipitated in a finely divided state in theprotein derivative and forms a stable dispersion therewith. Thedispersion can be diluted with a water-alkanol mixture to a properviscosity for coating and cast hyde solution containing 0.25 gm. ofsodium carbonate monohydrate. The mixture was stirred for two hours atroom temperature, a little dilute carbonate'solution being added fromtime to time to keep the mixture just alkaline to litmus.

The above solution was poured into 480 cc. of a stirred solution of zeinprepared by dissolving 125 ms. of zein in 3'75 cc. of ethanol and 25 cc.of water. The mixture was stirred and heated to reflux for five hoursand then poured into cold water. The plastic mass which separates waswashed with water and upon drying a somewhat brittle, brownish mass wasobtained. It contained structural units of the probable structure:

III-43H wherein the free bonds form a part of the protein residue.

Example 2 To 100 cc. of dioxane, l1gms. of zein were added at roomtemperature, followed by 15 gms. of, saligenin. The mixture was stirredfor one and one-half hours at room temperature and then heated to C. Atthis temperature, .75 cc. of phosphoric acid was added and afterstirring and heating for five minutes a plastic mass separated from theliquid. To'the mixture were added 50 cc. of alcohol whereupon partialsolution took place. Heating was continued for live hours more and aftercooling the liquid was decanted and the remaining solid washed withacetone and alcohol and then dried. The product was similar inappearance and properties to that described in Example 1.

Example 3 In a manner similar to that described in Example 2, zein (11gms.) and'saligenin (15 time.) were treated in dioxane with the additionof 4 gms. of benzaldehyde-o-sulfonic acid to the reaction mixture. Theresulting product was somewhat more water-sensitive than the products ofExamples 1 and 2. I It had the unit structure set forth in Example 1except that a portion of the CH: radicals were replaced by I CH zNa

radicals.

1 Example 4 A solution of 20 gms. of zein in 50 gms. of 85% formic acidwas treated at 45-50 C. with 10 of saligenin. The mixture was stirredand heated to 65 for one-quarter of an hour. After cooling and dilutingwith two liters of acetone, a viscous solid separated. The solid waswashed with fresh acetone and dried.

Example 5 ample 5 except that the -CHr-- radical was replaced by aradical of the formula:

ample 7 It in Example 6 the dimethylolurea was replaced by an equivalentquantity of bis-methoxymethylurea (22 gms.-), and 44 glue. or a, productwas obtained which was similar in properties and appearance andcontained the same linking radical as that in said example.

Example 8- To 200 cc. 'of dioxane which has been dried with solid sodiumhydroxide, gms. of zein and 5 gm. of benzaldehyde-orthosulfionic acidwere added with stirring. To this mixture were then A warm solution of245 girls. of 3-methyl-1- (m-aminophen'yl) -5-pyrazolone and 5 gms. ofpotassium carbonate in 1500 cc. of water was cooled to room temperaturewhereupon a fine crystalline precipitate was obtained. The suspensionwas added gradually at 20-30 C. to a stirred solution of 37%formaldehyde (111 cc.) containing 5 gms.

of sodium carbonate. After stirring for threefourths of an hour, themixture, which was acid to litmus, was poured into a stirred zeinsolution comprising 750 cc. of alcohol, 50cc. of water and 250 gms. ofzein. A pasty solid separated, but when stirred and heated, thesolidbroke up into granular particles. The mixture was stirred and heated to80 C. for several hours. After cooling and filtering and washing withwater, the bull, granular solid (305 31115.) was dried in the open air.It contained structural units of the probable structure:

/C 0-CH1 it l N: CH: III-CHr-N wherein the free bonds form part of theprotein residue.

Example 6 A solution of 24.5 gms. of l-(m-aminophenyl)3-methyl-5-pyrazolone and 5 gins. of sodium car solvent, 724 guns. of ayellow granular solid were a bonate in 250 cc. of water was added slowlyto a added 26 gm. of saligenln. After stirring for ten minutes and thenadding 1.5 cc. of sulfuric acid the mixture was warmed slightly. Thesuspended solid became pasty and cc. of alcohol were added whichpartially dissolved the suspended solids. Heating was, continued at 100for five to six hours with vigorous stirring. After cooling, actone wasadded to coagulate the product which was separated and washed well withpale plastic material was obtained. J

i'resh acetone. A total of 23 gms. of a Erammle 9 A solution was madecontaining 378 gms. (4 mols) of m-amino-phenyl-methwl-pyrazolone, 4

liters of H20, 50 gms.'ot sodium carbonate (mono j hydrate), 300 cc. of15.8% piperidine-alpha-carboxylic-acid. The mixture was stirred and madejust alkaline by addition of 500 cc. of 5% sodium carbonate. At 35-400., a solution of 240 gms;

of dimethylolurea in 1600 cc. of water was added rapidly. After adding500 cc. of alcohol the entire mixture was filtered to remove a smallamount of dark solid. After stirring for-one hour a solution of 1420 cc.of zein in alcohol was added with stirring at such 'a rate that no heavyclumping" took place. The zein solution had the followin compositions:alcohol 750 cc., water 50 cc., zeiu 250 gms. During the addition of thezein solution 250 co. more of alcohol were added. The mixture was thenheated with stirring to reflux for four to five hours. After cooling,preci itating with acetone and washing with the same obtained.

If in the previous example. formaldehyde is used in place ofdimethylolurea, the reaction mixture sets to a firm gel. After heatingfor two to three hours at this point, heating is interrupted, themixture is diluted with alcohol and then with acetone, slurried withacetone and filtered.

Example 10 In the manner described for Example 4, zein, formaldehyde andphenyl-methyl-pyrazolone were caused to react in formic acid solution.At the end of the reaction period, the product was precipitated withacetone, washed and dried as usual. It contained structural units of theprobable structure:

' is obtained.

wherein the free bonds form a part of the protein '-residue.

In the same manner zein, formaldehyde and acetoacetanilide were treatedin formic acid solution and the product recovered as before and aproduct containing the former units:

0 coon; f u f-cm- H wherein the free bonds form a part of the proteinresidue. X I

. Example 11 i A solution was made from the film-formin proteincolor-former obtained by the interaction of zein; formaldehyde andmeta-amino-phenylmethyl-pyrazolone after the manner described in Example5 as follows:

Protein color former gms Sodium hydroxide (20%)-. cc 10 Ethylalcohol cc100 Water ..cc.. 100

After stirring and warming until solution was complete, the liquid wasfiltered and treated with 5 gms. of light-sensitive silver bromide whichis substantially free from gelatin and was coated on a paper support atroom temperature. The resulting photographic element may be exposedthrough-a negative or to an original subject and processed in adeveloper such as the following;

- Grams p-Amino diethylaniline hydrochloride 2 Sodium carbonate(anhydrous) 20 Potassium bromide 5 Sodium sulfite 1 A very powerfulmagenta dye image is obtained.

' Alternatively, the element may be processed by reversal as follows:

Develop five minutes with intermittent agitation in the following firstdeveloper: N-methyl-p-aminophen'ol sulfate gms 5.0 Hydroquinone gms 7.5Sodium sulfite -.gms 60.0 Potassium bromide .'.gms 4.5 Water to cc..1,000

After washing in the dark for ten minutes, the film is exposed to lightand developed for ten minutes in the following:

p-Amino diethylaniline hydrochioride gms- 2.0 Sodium carbonate(anhydrous) gms 20.0 Sodium sulflte gms-- .5 Water to liters 1.0

After washing for fifteen minutes in running water, the film is bleachedin neutral or alkaline potassium ferricyanide, rinsed, fixed in plainhypo, washed and dried. A reversed magenta following probable color dyeimage of excellent strength and color purity I Example 12 pared from 311silver nitrate and 20% ammonia solution. The mixture was treated furtherwith 2 cc. of electrolyte free sodiumdodecyl sulfate (10%) and theresulting emulsion was coated at room temperature on a cellulose acetatefilm base having'a substratum coating of the type described in UnitedStates Patent No. 1,947,160. when this element is processed as inExample 11 by Y negative color development, a powerful magentadye imageis obtained. Alternatively as in Example 11 the element may be processedby reversal to yield a positive magenta image.

Example 13 Any of the products described in- Examples 1 through 4 may beused as, dispersing and binding media for light-sensitive silver saltseither byprecipitation of said salts therein or by addition ofcentrifuged silver salts to solutions of the pro tein color-formers.These blue-green color forming protein polymers were treated in themanner of Example 12, by precipitating silver bro de therein. Whendeveloped in an N-diethyl-paraphenylenediamine developer as described inExample 11, blue-green imagesflwere obtained.

Example 14 I A two-color component photographic'element was obtained asfollows:

On one side of a transparent support was coated-a light-sensitivemagenta protein color-forming layer similar to that described in Example11 or in Example 12. On the opposite side of the support was coated ablue-green protein colorforming iayer similar to those obtained. asdescribed in Example 13, using the protein colorformers as described inExamples 1 through 4.

The resulting two-co or component element may be used, for. example; forprinting from color separation negative records of an original sub-'ject using the red and green record for printing on the blue-green andmagenta side respectively,

of the two color element. After developing in anN-diethyl-para-phenylenediamine developer as described inExample 11,blue-green and magenta images remained in superposition. The,

blue record.negatlve may be converted into a positive yellow componentimage on the two color image by toning, imbibition, or other suitablemeans.

- Example 15 cipitated silver halide which has been sensi? tized for redby means of naphthoselenocarbocyanine iodide to a composition derivedfrom one of the blue-green protein color formers described above. (B)Over this layer is coated a separating strata consisting of partiallyhydrolyzed ethylene-vinyl-acetate interpolymer. (C) Next is coated acolor yielding layer similar to that described in Example 11 with theexception that the pro-precipitated silver bromide has been madesensitive to blue and green by means of erythrosine. (D) Next in orderis coated a yellow resin colloidal silver element such as that which maybe obtained by reducing a solution of silver nitrate in awater-insoluble, water-permeable colloid, e. g., by means of diphenylcarbazide. (E) Finally there is coated a layer of a asa'naov yellowprotein color former containing light sensitive silver salts. The coloformer which is employed may be that described in Example as obtainedfrom acetoacetanilide. This film may be exposed and developed innegative color developer as described in Example 11, whereupon anegative image in complementary colors will be obtained. The iilm mayalso be processed by reversal using the black and white first developerand color developer described in Example 11'. In this case,,a positivecolor image giving an approximate reproduction of the original subjectwill be obtained.

In place of the zein described in the above examples may be substitutedother veget'able proteins in similar amounts whereby color formers aredirectly linked to the protein nuclei through an ether linkage. Suitableproteins include gliadins or prolamines such the gliadin of wheat, zeinof maize, and hordein of barley which are soluble in 70-80% alcohol;glutelins such as gluten from wheat and maize and oryzenin from rice,which are soluble dilute alkalies and acids but not in neutral media;giobulins such as edestin from hemp, phaseolin from beans andtheglobulins of wheat which are soluble in dilute acids and alkalies;albumins such as ricin from castor beans, leucosin from wheat, legumelinfrom peas and vetches which are soluble in water.

matic, e. g., benzoylacetanilide, p-nitrobenzoyl- Zein derivatives suchas piperidylmethylzein, dimethylaminomethylzein anddimethylaminoethylzein and related derivatives can be used.

A wide variety of color formers or dye intermediates can likewise besubstituted in the above examplesor with the alternative proteins de- 35scribed above to form similar hydrophilic protein color formers. Thepreferred reaction for preparing these new color forming binding agentsinvolves formation through formaldehyde to give a compound having eachof the color forming nuclei attached through a methylene (-CHa-) groupto a nitrogen atom of an amido group or to a carbon atom which is inturn attached to a nitrogen atom in the chain of atoms forming thepolymeric protein molecule. The color-forming nuclei .need not, however,be attached directly to the methylene group. For instance,non-color-forming formaldehyde reactive groups. e. g., amide, mercapto,or aliphatic amino or hydroxyl may be present in the dye intermediate orcolor former and react with formaldehyde to form methylol derivativescapable of condensing with the amino groups of the protein to form alateral color forming substituent. The solubility and permeability ofthe protein derivatives may vary considerably depending upon theproperties of the initial protein used, the nature of the bi-iunctionalcondensing agent, and the nature and number of color formers condensed.If color formers which contain solubilizing groups, e. g., sulfonic acidor carboxylic acid groups 'are used the water-sensitivity of theresulting pro.- tein derivative is increased. If the protein colorformers do not have sufficiently high watersensitivity or solubility,solubilizing groups such as carboxylic or sulfonic acid, groups can beintroduced, by reaction with glyoxal, or with formaldehyde andhydroxythane sulfonic acid or glycolic acid. If the products are toowatersensitive, insaiubilizing groups may also be introduced, forinstance, by an amidation reaction, a. g., by condensation with fattyacid chlorides such as acetyl chloride, lauryl chloride, stearylchloride, etc., or with aromatic acyl halide, e. g.,

benzyl chloride. The modification of the solubility characteristics ofthe proteins can be accomplished prior or subsequent to the condensationof the dye intermediate or color former 5 therewith. 1

In addition to-the color formers or dye inter mediates used in the aboveexamples, there'may be employed many or the other well-known compoundsof this type. Thus the dye intermediate 1 nucleus may beany phenol,naphthol, or am;

matic amine having a coupling position available ortho or para to thealiphatic hydroxyl or amine group or anyactive methylene compound, 1.e., any compound having" a CH-.- group activated by two'vicinalunsaturated groups taken from the class consisting of -coo alkyl, cobaryl connected either directly or through a conjugated system. Suchactive methylene compounds are distinct by their ability to have one ofthe hydrogen atoms of the methylene groups replaced by alkali metals "inan aqueous solution'and include a host of acyclic and heterocycliccompounds. Examples of such active acyclic and intercyclic methylenecompounds include (1) beta-ketoacylamides of the type RCOCHzCONHR, whereR is a hydrocarbon or heterocyclic radical and R is preferablyaroacetanilide, p-nitroacetoacetanilide, naphthoyacetanilidep-acetoacetamidobenzoic acid,"'furoyllone, 1-m-sulfophenyl-3-methyl 5pyrazolone,

(3) indoxyl and thionindoxyl, (4) N-homophthalylamines, e. g.,N-homophthalylaniline, N-homophthalyl-n--dodecylamine,.N-homophthalyl-betanaphthylamine, (5)2,4-dihydroxyquinoline, (6) p-nitrobenzylcyanide, (7) diketohydrindene,(8) malonamides, e. g., ethyl N-phenylmalonam'ate,N,N-diphenylmalonamide, (9) phenacylpyridinium bromide, (10)hydroxypyridine, (11) cyanoacetanilide, ethyl/cyanoacetate.

In the method of preparing these polymeric color-forming binding agentsemploying formaldehyde to connect the color former to the vegetableprotein chain, the formaldehyde may be in any form. Thus, it can be usedas solid paraformaldehyde or-dissolved or suspended in water or solventsfor the color former, or as formaldehyde-releasing compounds such astrioxane, hexamethylenetetramine, methylene diacetate. Compounds whichform methylol derivatives such as chloromethyl other may be used.Alternatively,

other bi-functional condensing agents, e. g., di- -methylol derivativesof amides, ureas, etc., e.- g.,

dimethylolurea, dimethyloladipamide, dimethyloloxamine and their etherssuch as bismethoxymethylurea may be used in place of formaldehyde forlinking the dye intermediates to the polymer chain.

The light-sensitive color yielding compositions described above whichconsist of a hydrophilic protein dye intermediate or color former and alight-sensitive silver salt can be madewith a. wide variety of silversalts. Thus simple and 70 mixed silver chlorides, bromides and iodidescan be incorporated with the novel color former as binding agents. .Thedispersion may advantageously be made by dissolving the hydrophilicprotein color-dormer in a solvent thereforand '15 mixing a water solubleinorganic halide thereyl-5-pyrazolone, l-phenyl-3-carboxy 5pyrazowater-soluble silver salt. Suitable solvents for the proteinderivatives include-water containing -50 per cent of a water-misciblevolatile al-v aae'aso': I v

which in the form oi thin layers, e.-g., one 'to ten or more microns inthickness are. insoluble in water at C.. but are freely water-permeable.They should moreover be soluble to the extent of kanol, e. g., methanoland ethanol. The water 5 5 parts by weight in 100 parts of aboilingaquesoluble inorganic halides, e. g., sodium bromide, potassiumbromide, ammonia bromide and the corresponding chlorides and iodides maybe simply dissolved in water. Similarly, water 'soluble ous solutioncontaining less than 50 and preferably less than percent of ethanol. I

An advantage of the new film element's o fthis invention resides .in theincreased ability of the silver salts such as silver nitrate, silversulfamate, l0 dye images formed. Another advantage resides silvercitrate, silver acetate can ealso be added from water solution. Thesilver halides are prepared in the hydrophilic protein color formerwhereby a light-sensitive colloid composition is formed. Itcan befurther treated to improve its 15 photographic properties by theprocedures employed with gelatino silver halide emulsions. For

instance, the hydrophilic protein color former can be coagulated,washed, ripened, free from excess soluble salts adjusted to the desiredpH, digested 20 and then coated. As desired the compositions may be setand shredded for later use'in coating solutions.

Various types of sensitizing dyes which modify the spectral sensitivityof the resulting emulsion 5 sensitizing gelatin silver halide emulsions.Similarly,'emulsion sensitizers, e. g., sodium thio--3o sulfate andsodium hyposulfite; ailyl thiourea. allylisothiocyanate and anti-foggingagents, e. g., benzimidazole, nitrobenzimidazole, benzotriazole,and'methyl thiouracil; preservatives, e. g., thychrome alum, potassiumalum, formalin, and dimethylolurea; and other emulsion constituents canbe used if desired at various stages preferably prior to coating. 1

in the toughness and flexibility of the light-sensitive layers. Afurther advantage resides in the* fact that the color yieldinglayersprpd'uc'e the maximum color. density obtainable from the amount ofsilver salt reduced by the color cou pling development. This admits of asaving of ing a greaterdegree of definition and resolution than isobtainable by the use of immobile color formers in gelatin silver halidelayers.- J I The products of this invention have wide utility in colorphotography. They can be utilized as a direct taking stock or induplicating or copying and in making color prints on paper. Any num- Iber of color positives 'can be producedirom a single color negative madeand treated in accord- .mol, menthol, and alcohol; hardeners, e. g.,ance with the above procedures. The color negatives or positives can beused for preparing color separation negatives or positives by varyingthe utility in processes of color photography involv- The final coatingcompositions can be applied 40 ing the formation of azo dye images.Thus, they to a support or to a water-permeable colloidal layer on asupport in the .same manner that gelatino silver halide emulsions arecoated. After drying the resulting elements can be exposed and\processed in ,various manners to form colored images.

Multilayer films other than those described in the above examples maybeprepared accordin to this invention. Thus, the layer for recordin redlight and producing the blue-green part image may be sensitized to greenand red light both and protected by a green absorbing red filter layerbetween it and the exposure, or the sensitive layers may be coated in adiflerent order.

or one of these layers may on the other side of the support. Inaddition, the present invention can be applied to a two-color process bysuitable selection of dye intermediate nuclei and sensitizing compounds.Further, the invention can be combined with other processes forproducing 001- to ored photographic images. For example, in the case ofa three-color film, two-color images may be produced on one side of thesupport by the limited to the specific embodiments described I above asmany apparent widely different embodiments of the invention maybe madewithout departing from the spirit and scope thereof.

What is claimed is: l. A color yielding element comprising a supportbearing at least one layer composed of a hydrophilic vegetable proteincolor former, said compound having a plurality of color former groups,each being linked by a carbon to carbon linkage to 9. CH2- group to anamino nitrogen process of this invention, whereas the remaining a 1 atomof the prote n molecule. each color former color image may beproduced.'for example, on

the other side of the support by toning or on the same side by animbibition process. The term hydrophilic as used in this applicationwhen referring to the color formers or dye intermediates is intended todenote vegetable protein color group containing in one of its tautomericforms a composition of the structure a ti e where X is taken from thegroup of primary amino, secondary amino and hydroxyl groups and n is anumber from the group consisting of 0 and 1. said layer havinglight-sensitive silver coupling development oisilver salt mages 21 i 715halides dispersed therethrough.

of light occurs. This results in faster films havthrough.

2. An element as defined in claim '1 wherein the protein is zein.

3. A color yielding element comprising a support bearing at least onelayer composed of a a hydrophilic vegetable protein color former, saidan s where X is taken from the group of primary amino, secondary aminoand hydroxyl groups and n is a number from the group consisting of 0 and1, said layer having light-sensitive silver halides and a sulfursensitizer dispersed there- 4. A color yielding element comprising asupport bearing at least one layer composed of a hydrophilic vegetableprotein color former, said compound having a plurality of color formergroups, each being linked by a carbon to carbon linkage to a CHagroup toan amino nitrogen atom of the protein molecule, each color former groupcontaining in one of its tautomeric forms a composition of the structurewhere X is taken from the'gr'oup of primary

